THE CONNECTIVE SUBSTANCE GROUP. 73 



In some cases better results are obtained by the use of chloride 

 of gold. The method is as follows : Freeze a small portion of 

 a tendon, then make the thinnest possible section, acidulate it 

 slightly and immerse in a per cent, solution of chloride of 

 gold until a strong.yellow color has been obtained, then soak in 

 a i per cent, solution of dilute acetic acid and expose to the 

 sunlight until a purple or reddish color has been obtained. 

 This will take a variable time, and is not always successful, for 

 reasons which are not easy to understand. 



At considerable distances from one another there will be 

 seen small dark bodies, which are the corpuscles already de- 

 scribed. It is difficult to determine whether or not these cor- 

 puscles are connected together. To isolate them, take a small 

 piece of young tendon- tissue, immerse three or four days in a 

 10 per cent, solution of common salt, and then tease. In this 

 way the cells may be liberated, and they will prove to be irre- 

 gularly flattened plates. 



Sometimes they lie at the intersection of several bundles 

 and then have separate expansions for each bundle ; the plates 

 then lie at various angles with one another, and if one be seen 

 edgewise it looks as if the corpuscle proper were traversed by 

 a line. 



Silver or gold, the latter especially, is generally necessary 

 to show the corpuscles in old tendons. The same method 

 shows the fibrillated tissue to advantage. The large tendon 

 bundles are often covered with endothelium (connective-tissue 

 corpuscles), which are continuous and form a complete invest- 

 ment. 



For the smaller bundles the tendon- corpuscles do not by 

 any means form a connected sheath. In very young tendons 

 they are quite near to one another, though even at this time 

 they only form a partial investment for the bundles ; but as 

 the tendon grows older the corpuscles become smaller, with- 

 draw from one another, and sometimes almost disappear. 



Tendon bundles, like other forms of connective tissue, are 

 often encased in a transparent, delicate membrane, not unlike 

 the sarcolemma of striped muscular tissue. It is well shown 

 by immersing the tendon in a dilute solution of acetic acid. 



Fat tissue. The ordinary fibrillated connective tissue often 

 becomes the deposit for oil, which fills the corpuscles, making 

 them swell out enormously. This is fat tissue. An excellent 



